The brightest pure-H ultracool white dwarf

Дата и время публикации : 2012-09-06T20:27:43Z

Авторы публикации и институты :
S. Catalan
P. -E. Tremblay
D. J. Pinfield
L. C. Smith
Z. H. Zhang
R. Napiwotzki
F. Marocco
A. C. Day-Jones
J. Gomes
K. P. Forde
P. W. Lucas
H. R. A. Jones

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 5 pages, 7 figures, accepted for publication in A&A Letters
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: We report the identification of LSR J0745+2627 in the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool white dwarf with kinematics and age compatible with the thick-disk/halo population. LSR J0745+2627 has a high proper motion (890 mas/yr) and a high reduced proper motion value in the J band (H_J=21.87). We show how the infrared-reduced proper motion diagram is useful for selecting a sample of cool white dwarfs with low contamination. LSR J0745+2627 is also detected in the Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). We have spectroscopically confirmed this object as a cool white dwarf using X-Shooter on the Very Large Telescope. A detailed analysis of its spectral energy distribution reveals that its atmosphere is compatible with a pure-H composition model with an effective temperature of 3880+-90 K. This object is the brightest pure-H ultracool white dwarf (Teff<4000 K) ever identified. We have constrained the distance (24-45 pc), space velocities and age considering different surface gravities. The results obtained suggest that LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the closest ultracool white dwarfs.

Category: Physics